This fish was only observed one time in a bathysphere by a man named William Beebe in November 22, 1932 off the coast of Bermuda. It looked much like a giant dragonfish. It was named Bathysphere intacta.
It was described as having strong pale-blue lights on its side, and having 2 ventrical tendrils each tipped with a blue or red light. Bathysphaera intacta, as its scientific name was suggested as, was 6 feet long while normal dragonfishes are only 15 inches long. It was seen in the North Atlantic Ocean at a depth of 2,100 feet. Average dragonfish are carnivores which prey upon small marine invertibrates, fish, and squid, so this larger creature could possibly kill a small person.
It is known in the "Mysterious Creatures" series as a group of cryptids called Beebe's abyssal fish.
What could it be?
As Darwin's theory shows, some animals adapt slowly to their surroundings meaning it could be an oarfish that adapted to become a carnivore in order to eat marine snow, the main food source in the abyssal zone. However, the evidence of the Meganeura and other giant bugs in the Paleozoic Era being massive due to the large amounts of oxygen shows that it could have lived in a highly oxygenated part of a cave due to loads of plants and grown massive.